Piling method

ABSTRACT

To manufacture a pile which is intended to take compressive as well as tensile loads or to serve as a reinforcement member in soils, a strip is wound off a roll of strip material and is carried through a rotating-roller shaping unit in which the strip is shaped by rollers. If desired, the unit is operated in such a manner that it forms a bend in the direction of pile advancement. A pile thus shaped is driven from the roller shaping unit by means of pressure in arbitrary directions into the mass of an earth layer. Upon attainment of the desired depth of penetration and/or pile length the pile is severed at or close to the upper surface of the earth layer.

BACKGROUND OF THE INVENTION

The present invention relates to a method of manufacturing piles in situimmediately prior to the use thereof for foundation, groundreinforcement or soil stabilization purposes.

In conventional piling operations, piles made from concrete, wood orsteel are generally used. Whichever type of pile that is used, thelength of the manufactured pile is generally restricted, although thepile lengths may vary from a few meters up to several tens of meters. Itis quite difficult to handle and manipulate very long piles, and todrive them down into the ground requires machinery equipped with a hightower. Shorter piles must be formed with interconnecting means allowingthe piles to be joined together, and such interconnecting means oftenincrease the pile manufacturing costs considerably, in addition to whichthe operations of joining the pile sections together during the pilingwork is quite time-consuming.

In conventional piling operations the piles are usually driven down intothe ground with the aid of some kind of percussion equipment. Suchequipment generates heavy vibrations and noise when in use, which couldconstitute an environmental disturbance.

SUMMARY OF THE INVENTION

The present invention provides a method allowing various types of pilingoperations to be performed in a considerably more simple and thereforeless expensive manner, while at the same time reducing vibrations andnoise to a minimum.

The method in accordance with the invention is characterized thereinthat a strip, preferably made from steel, is wound off a roll and iscarried through a rotating-roller shaping unit of a king known per se,in which unit the strip is subjected to plastic deformation in itslengthwise extension, whereby the strip is imparted with a desiredpredetermined cross-sectional profile configuration, that the pile thusshaped, when leaving the roller shaping unit, is driven downwards orlaterally into an earth layer by means of pressure on the pile, and inthat, upon attainment of the desired penetration depth and/or thedesired pile, length the pile is severed level with or close to theground surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the pile in accordance with the invention and themethod of driving the pile into the ground will be described in closerdetail in the following with reference to the accompanying drawings,wherein:

FIG. 1 is a lateral view of a utility vehicle fitted with the pilingequipment in accordance with the invention.

FIG. 2 is a cross-sectional view through a road embankment stabilized bypiling.

FIG. 3 is a sectional view through a slope stabilized in a similarmanner,

FIG. 4a through 4e show, by way of example, end views of various pilesin accordance with the invention,

FIG. 5 is a schematical plan view of an arrangement including fourinstallation shafts with an intermediate "pile wall", and

FIG. 6 is a lateral view of a modified embodiment of the utility vehicleillustrated in FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 illustrates a vehicle 1 serving as a utility vehicle whenperforming the piling operations. The vehicle is equipped on its upperportion with a roller stand 2 which supports a roll 3 of a stripmaterial 4. The strip 4 is carried over a deflector rail 5 and fed intoa rotating-roller shaping unit 6. The basic structure of this unit is ofa prior-art nature and includes pairs of rollers 7 which are designed toshape the initially flat strip blank during the successive advancementof the strip 4 into the desired predetermined cross-sectional profileconfiguration. A pair of driving wheels 8 formed integrally with theshaping unit 6 are positioned one on either side of the shaped strip.The purpose of the driving wheels 8 is to drive the pile 9 thus shapedby pressing it down to the desired penetration depth in the underlyingearth layers 10. Below the driving wheels 8, a severing means 11 islocated, by means of which the pile 9, when having been driven down intothe desired position, may be cut off at ground level. The severing meansmay be, e.g., hydraulically operated scissors.

The utility vehicle 1, which may be of moderate size, can then be movedto the next place of piling.

The shaping procedure is a rapid one. The strip 4 may be advanced at thespeed of some ten meters per minute, or even more. The pile 9 thusformed successively, may be installed in any desired direction.

FIG. 2 shows a situation according to which the earth layer 13underlying a road embankment 12 needs to be reinforced/stabilized. Withthe use of the shaping unit 6 it becomes possible, in accordance withthe teachings of the invention, to form piles 14 from the strip 4. Whilebeing driven down into the ground on one side of the road embankment 12,the pile 14 follows a curve in the vertical plane and thus it reappearsfrom the ground on the opposite side of the road embankment 12. Toanchor the ends of the piles 14, a shaft 15 may be excavated laterallyof the embankment 12. In this case, the primary purpose of the piles 14is to absorb tensile stress, and, in this manner, they act as soilstability reinforcement means. The installment of such curved profiledpiles 14 in accordance with the invention reduces the need of, e.g.,load-supporting embankments.

Owing to the considerable rigidity of the piles 14, they will attributeconsiderably to the resulting increased stability of the earth layer 13.The result is that, e.g., the effects of the dynamic load caused bymoving vehicles, such as trains, trucks and similar vehicles, which loadis transferred to the earth layer 13, may be reduced to a considerabledegree.

Similar soil stability improving measures may be taken also in layers ofloose and unconsolidated soils in order to reduce the effects ofdetrimental vibrations due to earthquakes.

FIG. 3 shows one exemplary application of the novel piling techniqueused for stabilization of a slope 16. The dash-and-dot line 17 marks theestimated potential sliding curve of sliding masses of earth in theslope 16. Conventional piling using percussion techniques often cannotbe recommended in situations similar to the one illustrated, because ofthe vibrations which are generated under such circumstances and whichcause displacement of considerable masses of earth during the pilingoperation. The stability of the slope could possibly be improved byproviding some kind of ground anchors inside the mass of the slope 16.However, the installment of such anchors is very costly.

In accordance with the teachings of the invention, two piles 9 couldinstead be forced down into the mass of the slope as illustrated in FIG.3, without generation of vibrations or displacement of large masses ofearth. As an alternative to or in addition to these piles 9, one orseveral curved piles 14 may be driven into the slope 16 in the mannerindicated in FIG. 3, either from the front or from above. The method andequipment in accordance with the invention thus allow improvement ofslope stabilitity in a manner which is both less expensive and saferthan the conventional technique used hitherto.

FIGS. 4a through 4e show examples of various pile profileconfigurations. From a geotechnical viewpoint it is essential that thepile possesses maximum rigidity and maximum surface area. FIG. 4dillustrates an embodiment the profile configuration of which is intendedto be obtained from a strip which, already when wound into the roll 3,forms a closed shape. As an alternative to driving a thus-shaped pileinto the ground it is possible to force it laterally into an earth layerin which case the shaping unit is positioned in a shaft. As soon as theprofiled strip is in position in the ground in such a manner that aftersevering of the strip it extends for instance between two shafts, itbecomes possible to apply an excess pressure in the interior of thestrip, whereby the strip expands into a tubular shape. The leading endof the profile strip should be closed in a suitable manner,

FIG. 4e shows an embodiment according to which the strip 4 is given aprofile configuration allowing one section, when positioned in theground in order to serve as a pile, to be hooked onto the adjoiningsection in the manner of a sheet pile, and, with the aid of such pilesections, it becomes possible successively to form a sheet pile wall.

FIG. 5 represents schematically an arrangement consisting of four shafts18 which are excavated in a circular array and which are spaced apredetermined distance apart. From the excavated shafts 18, piles 14 aredriven laterally into the earth in the manner taught by the invention,the shaping unit 6 then being set in a manner causing the piles toextend along a predetermined curved line in the horizontal plane fromone well or shaft to the next. In this manner it becomes possible toform "rib cage" pile walls which facilitate excavation operations in theentire ground area 19 interiorly of the shafts 18. Such "rib cage"structures could also be erected with vertically directed piles 14.

FIG. 6 shows a somewhat modified utility vehicle 1a. The roll 3 of stripmaterial is enclosed inside a cartridge 20 mounted on the roller shapingunit 6, the latter being articulated to an extension arm 21 on thevehicle 1a. The roller shaping unit 6 and the cartridge 20 are mountedfor joint pivotal movement by means of a hydraulic piston-and-cylinderunit 22, allowing them to assume various angular positions, eitherinwards towards the utility vehicle 1a, or outwards, as illustrated inthe drawing figure. This arrangement facilitates the insertion orforcing downwards of the pile 9, 14 into the ground under the conditionsoutlined above.

The pile 9, 14, in its various applications, is primarily intended to beused in loose soils, such as normally-consolidated clay. However, itcould also be used in more compact types of soil. The method inaccordance with the invention, when applied in clay soils, makes use ofthe principle that the force required when the pile 9, 14 is driven intothe ground is considerably smaller than the load-absorbing capacity ofthe pile. This is due to the "breaking up" of the soil withconsequential reduction of the strength which occurs as a result of theinstallation of the pile. The force required to drive the pile downwardsor inwards thus is reduced, which means that the equipment could be madeaccordingly smaller and more compact. By means of reversing pulses, theresistance of the pile against the driving-down into the clay is furtherreduced because of the increased "breaking up" of the clay. However, intime the clay settles and resumes its original strength.

By measuring the resistance of the pile against being driven down itbecomes possible to determine the load-bearing capacity of the pile.

A further application of the pile in accordance with the invention is asan anchoring member to resist lateral pulling forces, e.g. as sheet pileanchoring member. Hitherto, anchorage of this kind has consistedprimarily of stays (wires) which are secured in rock by means ofdrilling or in other types of anchoring bodies (injection zone). Forcinga pile 14 laterally into the soil in the manner in accordance with theinvention provides a more simple and less expensive solution to thisproblem.

The invention is not limited to the embodiments described in theaforegoing and illustrated in the drawings, but could be modified in avariety of ways within the scope of the appended claims. In order toreduce the weight of the strip 4 and in order to increase the efficiencyin certain types of soil, the strip 4 could be perforated prior to or inconnection with the profile-shaping process. During the shaping processit is also possible to form the strip 4 with bumps or projections.

The strip 4 could be pre-treated prior to the shaping process. It could,for instance, be covered with a coat of paint or it could beelectroplated. Other materials than steel could be used, such asaluminium.

What I claim is:
 1. A method for manufacturing a pile in the ground insitu, comprising:(a) providing a flat strip of plastically deformablepile stock material on a roll having a leading end, so that the striphas a length, a width and a thickness; (b) while unwinding the stripfrom the roll, leading end first, passing successive increments of theunwound strip through a rotating roller-type shaping unit whichplastically deforms the strip so that its profile, as seen in transversecross-section, becomes less flat and more bent than when said strip wason said roll; (c) while conducting step (b), by pressing longitudinallyforward on said unwound strip, forcibly driving said unwound stripdownstream of said rotating roller-type shaping unit into the ground todefine a pile; and (d) upon attainment of a desired length of insertionof said pile into the ground, severing said pile from said unwound stripat a point level with or close to the ground.
 2. The method of claim 1,whereinin conducting step (b), the unwound strip is provided by saidrotating roller-type shaping unit with a curvature about an axistransverse to opposite faces of said unwound strip, so that, as step (c)is conducted, the pile is inserted into the ground along a curved path.3. The method of claim 2, wherein:as a result of conducting step (c),the leading end of the pile emerges from the ground at a site remotefrom where the leading end of the pile was inserted in step (c), beforestep (d) is conducted.
 4. The method of claim 1, wherein:whileconducting step (c), the pile is inserted non-vertically into theground.
 5. The method of claim 1, wherein:step (b) further comprisesperforating successive increments of said unwound strip beforeconducting step (c).
 6. The method of claim 1, wherein:step (b) furthercomprises forming bumps on one face of said unwound strip andcorresponding depressions in an opposite face thereof, on successiveincrements of said unwound strip before conducting step (c).
 7. Themethod of claim 1, wherein:said strip is of flattened tubular form andsaid method further comprises the step of opening up a longitudinal borein the pile upstream of the leading end thereof after conducting step(d).
 8. The method of claim 1, further comprising:subsequent toconducting step (d), conducting steps (b) and (c) on a succeedingincrement of said strip, beside the first-installed said pile, and whilethus-installing a second said pile, hooking the second said pile withthe first-installed said pile, thereby providing sheet piling made ofsaid first-installed and second said piles.